A power supplying system for supplying power to a self-driving closure device in which a driving source for driving the closure device for opening and closing an opening moves together with the closure device includes a lead wire having one end connected to a power source and the other end connected to the driving source. The side of the lead wire connected to the power source is supported at a midpoint between the positions of the upper and lower limits of movement of the driving source, while the side of the lead wire connected to the driving source is supported in such a manner as to move together with the driving source. The lead wire is thus made to swing in conjunction with the movement of the driving source so as to supply power to the moving driving source. A guide shaft is provided along the direction of movement of the driving source, and a helical portion formed in the lead wire is extended or shrunk along the guide shaft so as to supply power to the moving driving source.